Carriage way unit for bridges and like structures



July 11, 1939. 1 GAlSMAN 2,165,846

CARRIAGE WAY UNIT FOR BRIDGES AND LIKE STRUCTURES Filed Sept. 29, 1957 By his Allomqy:

Patented July 11, 1939 PATENT OFFICE CARRIAGE WAY UNIT FOR BRIDGES AND LIKE STRUCTURES Lucien Gaisman, Woodley, near Manchester, England Application September 29, 1937, Serial No. 166,254 In Great Britain October 9, 1936 4 Claims.

This invention relates to carriage way units for bridges or other like structures such as tunnels where saving of weight and/or thickness are or is a material consideration. It has already been 5 proposed to provide a road surfacing slab or block consisting of a metal base formed with un dercut or dovetailed recesses and having a rubber surface vulcanised thereto consisting of a resi1- ient upper surface layer and a relatively hard under layer which is locked into the said undercut or dovetailed recesses. An example of such slab or block is described in British Patent No. 214,433. The cost of manufacture with a metal base other than by employing a cast metal base renders such block an uneconomic proposition.

Although such blocks with cast metal bases have been made and laid with success, there are economic and other reasons, when made in large units, which would preclude their universal adoption, especially for bridge construction in spite of certain advantages inherent in the rubber surface, such as silence and reduction of shock and vibration transmission to the rest of the structure.

All the above examples relate only to road paving blocks and have to be laid on a prepared road foundation, consisting usually of a deep bed of concrete.

Rolled steel is now a universal building material for engineering structures, but its manner of manufacture, which has enabled it to become an economic proposition, precludes the forma tion during rolling of a plate having dovetail or undercut key formations, necessary for the secure attachment of a rubber cap. Such forma tion could therefore only be provided by a subsequent machining process, the cost of which immediately prohibits its adoption.

The problem which this invention solves is the economic manufacture from rolled steel of bases which are themselves the foundation of the carriage way and which are provided with interlocking key formations suitable for capping with rubber by direct vulcanization thereon, in units of varying dimensions to provide complete carriage way units embodying both the foundation and wearing surface and suitable for bridge and like constructions.

The invention is in fact to a large extent based on an appreciation that the equivalent of an under-cut or dovetailed recess can be provided by a built-up structure from rolled steel without subsequent machining to form the undercut or dovetail.

According to the invention a carriage way unit for bridges and like structures comprises a base to which a rubber face is keyed, said base em.- bodying a load-carrying built-up assembly of rolled steel members, shaped, arranged and secured together so as to provide a composite girder 5 adapted tobridge a space between supporting members of a bridge or like structure.

The expression composite girder includes any arrangement of members secured together whichc individually or collectively provide de- 10 fined upper and lower flanges until by a web or their equivalent, as for example, I, T, channel or box formation.

In the accompanying drawing:

The figure is a part sectional perspective view of one example of a carriageway unit made in accordance with the invention.

As illustrated in the figure, the base of the carriage way unit comprises a solid flat rectangular rolled-steel back plate a about A; inch ,20 thick and 18 inches square to which is secured by welding at the edges and corners a plurality of flat segmental rings or tubes 2) with walls of rectangular cross-section formed as stampings or pressings from rolled steel plate, the rings or 25 tubes being open to the edges and corners of the plate and evenly spaced. Also spaced over the surface of the back plate and away from the edges and corners and welded thereto are com-- plete rings or tubes 0 of similar cross section and 30 size, and arranged in rows in line with the segmental edge rings, while between them are small er complete rings or tubes d also Welded to the back plate. Experiments made with rings or tubes of various thickness or axial length have 35 shown that the best results are obtainable when such length is about 1", with a base of the proportions above described. Also fillet welding is found to be much superior to spot welding. A top plate e, inch thick and of the same overall 40 dimensions as the back plate, is then welded on top of the segmental rings and complete rings, such plate having segmental edge or corner apertures f and round holes 0 adapted to register with the spaces within the segmental or com- 45 plete rings or tubes aforesaid, and of smaller size so that the top plate overhangs such spaces. Filling strips It may be provided around the edges of the plate.

A rubber cap thick is then applied to the base consisting of a lower hard vulcanising layer i with projections filling the under-cut spaces in the base, and an upper relatively resilient layer a.

In order to reduce the amount of rubber, particularly the more expensive hard rubber, the

bottom of the under-cut recesses may be filled with concrete or any suitable filling i leaving say a depth of under-cut space to be filled with the rubber. The segmental edge or corner recesses will preferably be completely filled with rubber.

Obviously the assembly above described provides segmental or circular under-cut key formations similar in arrangement and inter-locking effect to those described and illustrated in Patent No. 1,560,174, so that a rubber cap may be applied and vulcanised thereto so as to be keyed thereon. The back plate a may be perforated, as by punching to form holes i in the space within the segmental or complete rings, or some of them, to provide especially at the segmental portions, a further locking effect against displacement in the direction of the open side of the ring.

By this invention the base assemblies can be manufactured from rolled steel plate and stamp ings or pressings therefrom, the additional processing of assembly, stamping or pressing being a simple and economic possibility, compared with machining to produce dovetailing or undercutting.

The complete carriage way unit of steel base with its vulcanised rubber cap thereon, provides both the foundation and the wearing surface for the carriage way of a bridge or like structure, the unit being secured to the framework of the ridge by bolting, riveting or any other suitable method, the back plate for instance being drilled and tapped for a bolt, or having a nut or a bolt or a rivet welded to it.

What I claim is:

1. A rubber faced carriage way unit for bridges and like structures, comprising a base to which a rubber face is keyed, said base comprising a bottom plate, an apertured top plate and spacing pieces, arranged and secured between the top and bottom plates, comprising flat faced or ended rings or segments of rings or tubes having apertures larger than the apertures in the top plate and arranged below the same so as to provide, at

such apertures, undercut or dovetailed key formations.

2. A rubber faced carriage way unit for bridges and like structures, comprising a base to which a rubber face is keyed, said base comprising a bottom plate, an apertured top plate and spacing pieces, arranged and secured between the top and bottom plates, comprising fiat faced or ended rings or segments of rings or tubes having apertures larger than the apertures in the top plate and arranged below the same so as to provide, at such apertures, undercut or dovetailed key formations, said rings or tubes or segments thereof being of a thickness or axial length greater than the thickness of either plate.

3. A rubber faced carriage Way unit for bridges and like structures, comprising a base to which a rubber face is keyed, said base comprising a bottom plate, an apertured top plate and spacing pieces, arranged and secured between the top and bottom plates, comprising flat faced or ended rings or segments of rings or tubes having apertures larger than the apertures in the top plate and arranged below the same so as to provide, at such apertures, undercut or dovetailed key formations, and a filler arranged in the lower part of said rings or segments of rings or tubes to reduce the volume of said key formations.

4. A rubber faced carriage way unit for bridges and like structures, comprising a base to which a rubber face is keyed, said base comprising a bottom plate, an apertured top plate and spacing pieces, arranged and secured between the top and bottom plates, comprising flat faced or ended rings or segments of rings or tubes having apertures larger than the apertures in the top plate and arranged below the same so as to provide, at such apertures, undercut or dovetailed key formations, said rings or tubes or segments thereof being of a thickness or axial length greater than the thickness of either plate, and a filler arranged in the lower part of said rings or segments of rings or tubes to reduce the volume of said key formations.

LUCIEN GAISMAN. 

